EPIDEMIOLOGY AND PATHOPHYSIOLOGY OF OCCUP ATIONAL ASTHMA

Poorly estimated prevalence: Although occupational asthma is the most frequently encountered respiratory occupational disease, the exact pre valence is poorly estimated because a large number of cases go unrecog nized or unreported. Several studies concord that approximately 5% of all asthma cases are caused by workplace irritants. The recently organ ized National Observatory for Occupational Asthma should provide a bet ter estimation in France. Risk factors: The main risk factor is exposu re to the incriminated agent Atopy is not usually involved in flour as thma. Tobacco smoke is an associated factor which favors the developme nt of asthma. Several mechanisms: The pathogenesis of occupational ast hma caused by high molecular-weight molecules is the same as that in a llergic asthma. Th2 activation plays a major role. For low molecular-w eight molecules, the pathogenic mechanisms are less clear, mainly beca use of the wide variety of causal agents involved. (C) 1998, Masson, P aris.